Device for detecting at least one environmental influence

ABSTRACT

A device for detecting and/or transmitting at least one environmental influence, and a method for producing the same. The device comprises at least one receiver element and an evaluation circuit that is substantially composed of organic functional material.

CROSS REFERENCE TO RELATED APPLICATIONS

This is the 35 USC 371 national stage of international applicationPCT/DE01/04370 filed on Nov. 21, 2001, which designated the UnitedStates of America.

FIELD OF THE INVENTION

The invention relates to a device for detecting and/or transmitting atleast one environmental influence, to uses thereof and a method forproducing the said device.

BACKGROUND OF THE INVENTION

A photodiode, a photoelectric barrier, a solar cell, a humidity,pressure and/or temperature sensor are examples of a device fordetecting and/or transmitting at least one environmental influence, saiddevice comprising at least one receiver element that records anenvironmental influence and an evaluation circuit that receives,evaluates, possibly amplifies and transmits a signal from the receiverelement.

Devices of this type are known which are based on conventional inorganicsemiconductor materials such as silicon and gallium arsenide. Thesedevices, such as sensors for example, are produced in manufacturingprocesses of conventional semiconductor technology. The raw materialsused as well as the process steps result in the devices being expensiveand accordingly being used only very selectively.

However, since a comprehensive sensor technology has advantages forvirtually all areas of industry, energy, transportation and life ingeneral because it allows better recording of currently obtainingconditions and/or more efficient use of energy, there is a demand forcheaper devices of the aforementioned kind to be produced.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to provide a device fordetecting and/or transmitting at least one environmental influence whichis comparable in performance with the conventional devices from thesemiconductor industry and/or is cheaper in comparison with these.

There are essentially two approaches to achieve this object. On the onehand, at least one cheaper raw material can be used for the productionprocess; on the other, the complex production method used insemiconductor technology, comprising coating, patterning, etching andetching back etc., can be simplified.

Both these starting points are taken into account in the object of theinvention, which introduces the new organic semiconductor technology(integrated plastic circuits (IPC) and/or organic field effecttransistors (OFET)) in this field.

The object of the invention is a device for detecting and/ortransmitting at least one environmental influence, said devicesubstantially being composed of organic material and comprising at leastone receiver element which records at least one environmental influenceand/or converts this environmental influence into an electrical signaland at least one evaluation circuit which processes and transmits areceived signal. A further object of the invention is a method forproducing a device for detecting and/or transmitting at least oneenvironmental influence, in which method at least one receiver element,one evaluation circuit and/or an associated connection arrangement isconstructed by coating at least one substrate with organic material.Finally, an object of the invention is to use a device for detectingand/or transmitting at least one environmental influence in industry, inmonitoring/sensor technology and/or in transportation.

Any quantifiable impulse of the environment which can be converted intoa current and/or a voltage is referred to here as an environmentalinfluence. An example of this from nature is a solar ray, a change inatmospheric pressure or, in the industrial domain, an increase in theconcentration of a certain gas and a change in temperature and/orhumidity. All these influences can lead via suitably sensitive chemicalcompounds (which are present in the receiver element) to a situation inwhich a conducting material becomes non-conducting or substantially lessconducting and/or in which voltage or current is generated in a materialand/or that the electrical resistance in a material is changed. Theseeffects are measurable and can be converted into defined signals via anevaluation circuit or stored in order to generate energy.

Also conceivable is a tactile and/or pressure sensor in which anelectrical signal is generated by pressure, as in the case of a keyboardfor example.

A particularly advantageous embodiment of the device for detectingand/or transmitting at least one environmental influence has thereceiver element and an element of the evaluation circuit integrated ona substrate. This results in very compact devices which exhibit a largesaving in volume compared with the conventional devices of thesilicon-dominated semiconductor technology. While it is possible thatthe Si sensors are smaller than the new devices, more important as analternative is first and foremost the ease of attachment e.g. toflexible substrates and/or to substrates (package, packing) which arealready present in any case. This also opens up totally new uses for thedevices because, thanks to their cheapness, the devices according tothis embodiment can be used as single-use products and, thanks to theirsmall volume, are suitable for use as e.g. labels etc. Also possible bythis means is, for example, a form of pharmaceutical packaging which, bycomprising a corresponding device, can provide information on how longthe preparation has been stored and at what temperatures.

According to the embodiment of the device, it is a temperature, humidityand/or pressure sensor, a photoelectric barrier, an optical sensor, asolar cell and/or something similar.

According to an advantageous embodiment, the device can receive, processand forward (transmit) a plurality of environmental influences inparallel. Also, it is possible, for example, for the temperature,pressure and composition of a gas and/or liquid mixture to be detected,stored together with the duration and/or passed on to a closed-loop andcontrol system. A particular threshold value for temperature, humidity,pressure and/or light intensity can be measured and represented. Thisprocess can be either reversible and record the current value orirreversible, for example to indicate whether a deep-frozen product hasbeen briefly thawed out or whether a package/medicine was ever exposedto a high temperature or a high level of humidity. All previously knownapplication areas for devices for detecting and/or transmitting at leastone environmental influence can be realized by means of the newsemiconductor technology which is primarily based on organic materials.At the same time the choice of sensitive chemical compounds which can beused in the receiver element is unlimited and can be geared specificallyto the particular problem and/or developed for the particular task inquestion.

The term “organic material/functional material” as used here comprisesall types of organic, organometallic and/or inorganic syntheticmaterials referred to as e.g. “plastics”. This includes all types ofmaterials with the exception of the semiconductors which form thetraditional diodes (germanium, silicon) and the typical metallicconductors (e.g. copper, aluminum) which are mainly used in the contextof electrodes and/or contact pins. A restriction in the dogmatic senseto organic material as material containing carbon is accordingly notprovided. To the contrary, consideration is also given to the widespreaduse of e.g. silicons. Moreover, the term is not to be subject to anyrestriction with regard to the molecule size, especially to polymerand/or oligomer materials, but instead the use of “small molecules” isalso entirely possible.

The expression “substantially composed of organic material” serves toindicate that it is altogether possible for functional elements to befashioned also from metal, silicon or some other material.

A particularly advantageous embodiment is one in which at least oneorganic functional material such as e.g. the organic conductor, theorganic insulator and/or the organic semiconductor are identical in atleast one receiver element and in at least one element of the evaluationcircuit of the device. This embodiment is noteworthy by virtue ofparticularly advantageous production costs if an organic material isdeposited on multiple points of the substrate in a single operation e.g.by printing or coating using the doctor blade technique.

In the event that the change in temperature is received as anenvironmental influence, the conductor track of the receiver element,for example, can be composed of organic material such as polyanilineand/or be an organic conductor which changes its resistance at or abovea certain temperature in such a manner that it becomes an insulator orvirtually an insulator. This may be a reversible or an irreversibleprocess within the material. In any case the receiver element for thisdevice is furnished with an organic conductor in which a change intemperature either causes voltage or current to be generated by chargeseparation or leads to an abrupt change in resistance. The receiverelement is thus not only placed in a position to record and measure theenvironmental influence “temperature change”, but also to pass on asignal to the evaluation circuit. Examples of such a material are PTC(positive temperature coefficient) thermally sensitive resistors whichcan be produced from doped polycrystalline ceramic material based onbarium titanate.

In the event that the composition of a gas mixture such as e.g.atmospheric moisture is to be measured, an organic conducting materialcan be used in which, depending on the concentration of the material tobe measured, e.g. water in air, a current is generated in the conductortrack or there is a change in the resistance (for example through achange in solubility behavior, cf. PEDOT). Here, the change inresistance may be reversible or irreversible, depending on material.

In the event that the pressure is to be measured, organic piezoelectricplastics are known that generate a voltage when they are stretched orcompressed.

For light sensors there are also examples where the organic functionalmaterials of a diode are chosen such that they generate voltage underthe action of light and/or their physical properties change reversiblyor irreversibly.

According to an advantageous embodiment, the device amplifies recordedenvironmental influences or signals and transmits them in either linear(analog) or digital form.

According to an advantageous embodiment of the method, at least onelayer of organic functional material is generated on the substrate byprinting (e.g. pad printing, offset printing) or by application usingthe doctor blade technique, i.e. by structured deposition on a lowerlayer or the substrate or by introducing material into/filling inrecesses. It is particularly advantageous here that structured layerscan be generated simply by printing/application by doctor blade and donot have to be produced, as in traditional semiconductor technology, bymeans of photomasks and etching steps.

The preferred use of a device for detecting and/or transmitting at leastone environmental influence is in industry, monitoring/sensor technologyand/or transportation. In medical engineering such devices are ofinterest as single-use sensors.

For example, the device serves as a label or part of a label in order tomake clear which environmental influences the labeled object was exposedto. It can also be usefully attached as an RFID tag, as a postage stamp,on transport packaging, in a pharmaceutical product, in a deep-frozenproduct, on moisture-sensitive parts, as part of a photocell, and intoys. Not least, the device can serve as a temperature sensor(conversely, it can also be a mini-heater which can be controlled by theelectronics), as a pressure sensor (conversely, it can also be amini-speaker), as a gas sensor, and/or as a safety element (warning ofCO poisoning).

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail in the following withreference to six figures which show various embodiments of the presentinvention wherein:

FIG. 1 is a block diagram of a device for detecting and/or transmittingat least one environmental influence;

FIG. 2 is a sectional elevation view of a device for detecting and/ortransmitting at least one environmental influence;

FIG. 3 is a schematic diagram of a structure of a receiver element forreceiving at least one environmental influence;

FIG. 4 is a schematic layout of a simple organic field-effecttransistor, such as can be used as evaluation electronics;

FIG. 5 is an elevation diagrammatic view of a continuous coating processaccording to an embodiment of the present invention; and

FIG. 6 is a schematic diagram of a further embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a block diagram of the device for detecting and/ortransmitting at least one environmental influence 1. At least oneenvironmental influence 4 causes a change in a resistance in thereceiver element or sensor 2 and/or generates a voltage which eitherchanges and/or initiates a current flow to an element 3 of theevaluation circuit. The element 3 of the evaluation circuit is connectedto a supply voltage 5 and a ground 6. The evaluation circuit comprisesevaluation electronics based on organic field-effect transistors, withthe aid of which the received signal is transmitted by either digital oranalog means to signal output 7.

FIG. 2 shows a cross-section through a device for detecting and/ortransmitting at least one environmental influence 1. On the extreme lefton the substrate or carrier 9, which can therefore be e.g. flexible, inother words a film, can be seen the encapsulation 8, which can beapplied differently according to environmental influence, in other wordse.g. transparently or by chasing out the receiver element 2 (e.g. if thepressure or the gas composition is to be measured). Residing under theencapsulation 8 in the case shown is the receiver element 2, on whichthe environmental influence 4, e.g. light, heat and/or humidity(depending on the type of encapsulation) etc., acts through theencapsulation 8. Depending on which environmental influence is to bereceived, the encapsulation for this is permeable or exposed at thereceiving point.

Also located under the encapsulation 8 is the element 3, which comprisesthe organic evaluation electronics. Outside of the encapsulation 8 arethe output signal and/or the connecting contacts 7. Depending on sensortype, the actual sensor element may also be located outside of anencapsulation, e.g. humidity sensor.

FIG. 3 shows the simplest schematic structure of a receiver element 2which can receive an environmental influence, e.g. light. Here can beseen the device 10 for measuring the photovoltage or the photocurrent,which is connected via a first feed line 11 to a first organic conductormaterial 12. The light 4 strikes this first organic conductor material12 and generates current or voltage, e.g. by charge separation in thematerial. This current travels through the organic semiconductingmaterial 13 and flows to the second conductor material 14, which isconnected in turn via the second feed line 15 to the device 10 formeasuring the photovoltage or the photocurrent.

FIG. 4 shows a schematic layout of a simple organic field effecttransistor, such as can be used as evaluation electronics. Mounted at adistance from each other on a substrate 9 are two electrodes, the sourceS and the drain electrode D, which are connected through a layer tosemiconducting organic material 18. The drain electrode C is connectedto the supply voltage 5 and the source electrode S is connected to theground 6. The upper gate electrode G is connected to the feed line ofthe receiver element 2. As soon as current flows via the receiverelement 2 to the gate electrode C, a conducting channel 16 is generatedin the semiconducting layer 18 between the source and the drainelectrode owing to the resulting field effect which acts through theinsulator layer 17.

FIG. 5 illustrates a continuous process which includes a conveyor belt22 which is displaced in direction 28 by a drive mechanism (not shown).A film substrate 24 is on and conveyed by belt 22. The substrate carriesa recessed mold layer 30 in which circuit recesses 32, 34 and 36 werepreviously formed in the mold layer by known techniques. A doctor blade38 applies a coating 40 of organic material into the recesses 32, 34 and36 in a continuous process to form a receiver circuit 42, an evaluationcircuit 44 and connections 46. A continuous process using a doctorblade, by way of example, is disclosed for structuring an OFET incommonly owned U.S. Pat. No. 6,960,489 which matured from an applicationcited in applicants' disclosure statement filed Sep. 30, 2004 andpublished as a PCT application WO 02/19443 on Mar. 7, 2002.

FIG. 6 shows a cross-section through a device 48, which is somewhatsimilar to the device 1 of FIG. 2, but is for detecting at least oneenvironmental influence such as the concentration of material in theenvironment. Encapsulation 52 on the substrate 50, which may beflexible. e.g.. a film, is applied to expose the receiver element 54 tothe surrounding atmosphere for detecting the material in theenvironment, which in this case is a gas composition to be analyzed.Also, the organic evaluation electronics 56 is covered by theencapsulation 52. Connecting contacts 58 are external the encapsulation52. A closed loon circuit and control 60 is coupled to the contacts 58by conductors 62.

1. A device for detecting at least one received environmental influencecomprising: at least one active receiver element substantially composedof organic material and which receives the at least one receivedenvironmental influence, the receiver element being responsive to theincidence of the environmental influence thereon to generate a firstoutput electrical signal manifesting the value of the at least oneenvironmental influence incident upon the receiver element and whichelement converts the at least one received environmental influence intothe generated first electrical output signal; at least one evaluationcircuit which processes and transmits the electrical signal appliedthereto as a second output signal therefrom, said evaluation circuitcomprising at least one organic field effect transistor, said secondoutput electrical signal manifesting the received environmentalinfluence; and an encapsulation media that is transmissive of thereceived environmental influence for encapsulating the at least onereceiver element with the encapsulation media through whichencapsulation media the received environmental influence passes forreception by the at least one receiver element.
 2. The device accordingto claim 1 further including an arrangement including a plurality ofsaid device which are arranged to receive and process multipleenvironmental influences into corresponding ones of said signal andtransmit the respective corresponding electrical signals therefrom inparallel and/or sequentially.
 3. The device according to claim 1,wherein the evaluation circuit includes at least one element comprisingthe field effect transistor, the organic material being identical in theat least one receiver element and in the at least one element of theevaluation circuit.
 4. Method for producing an electronic organic devicefor detecting at least one environmental influence comprising: coatingat least one substrate with organic material thereby forming on the atleast one substrate: a. at least one active receiver elementsubstantially composed of organic material for receiving and detectingat least one environmental influence and for converting the at least onereceived and detected influence into a first electrical output signal bygenerating the first output signal in response to the receipt of thedetected influenced; b. an evaluation circuit responsive to theelectrical signal for producing an evaluation signal, the evaluationcircuit comprising at least one organic field effect transistor; and c.an associated connection arrangement for interconnecting the evaluationcircuit with the at least one receiver element; and then encapsulatingat least the at least one receiver element with an encapsulation mediapermeable to the detected at least one environmental influence. 5.Method according to claim 4, including the step of applying the coatingat least partially by printing and/or introducing the coating materialby a doctor blade.
 6. Method according to claim 4, including the step ofapplying the coating in a continuous process.
 7. A device for detectingat least one received environmental influence excluding light,comprising: at least one active receiver element which is substantiallycomposed of organic material, the receiver element for outputting anelectrical signal in response to the receipt of the environmentalinfluence, the receiver element for generating the outputted electricalsignal by converting the at least one received environmental influenceinto said generated electrical output signal; at least one evaluationcircuit which processes and transmits the electrical signal appliedthereto and comprising an organic field effect transistor; and anencapsulation media for encapsulating the at least one receiver element,the encapsulation media being permeable to the received environmentalinfluence for transmitting that received environmental influencetherethrough.
 8. The device of claim 7 wherein both the receiver elementand the evaluation circuit are encapsulated with the encapsulationmedia.
 9. A sensor device for detecting at least one receivedenvironmental influence comprising: at least one active receiver elementfor receiving the at least one environmental influence, the receiverelement being substantially composed of organic material and forgenerating a first electrical output signal in response to the receiptof said at least one environmental influence by converting the receivedat least one environmental influence into the generated first outputsignal whose value manifests the received at least one receivedenvironmental influence; at least one evaluation circuit comprising anorganic field effect transistor which processes and transmits the firstoutput electrical signal applied as an input thereto; an encapsulationmedia for encapsulating the at least one receiver element and fortransmitting the received at least one environmental influencetherethrough to the at least one receiver; and the at least oneevaluation circuit comprising an arrangement associated with the atleast one receiver element and responsive to the first output signalapplied thereto as an input for producing a second output electricalsignal.
 10. A device forming a security element for detecting at leastone received environmental influence comprising: at least one receiverelement that is substantially composed of organic material and whichconverts the received environmental influence comprising theconcentration and/or the aggregate status of a material in theenvironment into an electrical signal; at least one evaluation circuitwhich processes and transmits the electrical signal applied thereto; anencapsulation media for encapsulating the at least one receiver element;the at least one receiver element being arranged to analyze at least theconcentration and/or the aggregate status of a material in theenvironment and converts this analysis into the electrical signal; and aclosed-loop and control system for controlling the device.